ST. PETERSBURG, September 28 (RIA Novosti) - About a hundred Russian and foreign dignitaries, including members of royalty, gathered in St. Isaac's Cathedral in St. Petersburg Wednesday for services to commemorate a Danish-born tsarina before she is laid to rest in her adopted homeland.

The remains of Maria Fyodorovna, the wife of Tsar Alexander III and mother of Russia's last monarch, Nicholas II, were brought to the former Russian imperial capital Tuesday to be reburied next to her family, in keeping with her final wishes.

Later on Thursday, a sarcophagus with the tsarina's remains will be buried in a crypt in the Cathedral of Saints Peter and Paul, the final resting place of members of the Romanov dynasty, which ruled Russia for more than 300 years.

Danish Princess Marie Sophie Frederikke Dagmar, baptized a Lutheran, took the name Maria Fyodorovna when she converted to Orthodoxy and married into the Russian imperial family at the age of 19.

She left Russia two years after the overthrow of the monarchy in 1917, and spent the rest of her life in Denmark, where she died in 1928.

Maria Fyodorovna's son - Russia's last tsar, Nicholas II - and her daughter-in-law and grandchildren were killed by the Bolsheviks in the Urals city of Yekaterinburg in 1918.The purported remains of Nicholas II were reburied in St. Petersburg in July 1998.